Resin bottles, typical examples of which are oriented polypropylene (OPP) bottles and polyethylene terephthalate (PET) bottles, are used in a variety of applications, such as beverage applications, food applications, and cosmetic applications. Such a bottle is typically formed into a predetermined shape by heating a resin preform formed to have a bottomed shape for example by injection molding to a temperature which can have a stretching effect and biaxial stretch blow molding in this state using a blow molding apparatus.
As a blow molding apparatus, a liquid blow molding apparatus is known, which is configured to use a pressurized liquid instead of pressurized air as a pressurized fluid supplied into a preform. In the liquid blow molding apparatus, when a content liquid such as a beverage, a cosmetic product, a pharmaceutical product, or the like to be eventually poured as a product into a bottle is used as the pressurized fluid, the filling of the bottle with the content liquid can be omitted. Thus, the production process and the structure of the production apparatus can be simplified.
For example, JP 2013-248748 A (PTL 1), JP 2014-506843 A (PTL 2), and WO 2014/180805 (PTL 3) disclose a liquid blow molding apparatus comprising: a metal mold having a cavity in which a trunk of a preform is disposed; a nozzle connected to a mouth of the preform; a seal body movable between a closed position where the seal body abuts an inner surface of the nozzle to close the nozzle and an open position where the seal body is kept away from the inner surface of the nozzle to open the nozzle; and a stretching rod vertically movable relative to the seal body, in which a pressurized liquid is introduced into the preform from the nozzle to stretch the preform at least radially by moving the seal body from the closed position to the open position, and the preform is axially stretched using the stretching rod, thereby forming the preform into a container having a trunk of a shape conforming to the cavity.
Further, the liquid blow molding apparatus disclosed in PTL 1 includes a rod guide interposed between the seal body and the stretching rod to suppress misalignment in the radial direction of the stretching rod with respect to the seal body and to seal a gap between the seal body and the stretching rod in a fluid-tight manner.